Skin and hair cleansing agents have recently been required to not only demonstrate cleansing strength, but also demonstrate foam qualities such as superior foaming power, foam fineness, elasticity and staying power, as well as a superior feeling after cleansing. Although fatty acid soaps and amino acid-based surfactants are frequently used for the main ingredients of skin and hair cleansing agents, in the case of using these surfactants, although foaming power was superior, foam quality and a moist feeling after rinsing were inadequate.
Examples of cleansing agents having superior cleansing strength as well as a favorable feeling after cleansing include a cleansing agent having an improved feel during use in the form of the cleansing agent containing an anionic surfactant, an amphoteric surfactant and 12-hydroxystearic acid disclosed in Patent Document 1. In addition, an aqueous skin cleansing agent is disclosed in Patent Document 2 that contains a foamable surfactant, a hydrocarbon-based paste-like oily agent, and a non-hydrocarbon-based paste-like oily agent. Patent Document 3 discloses a cleansing agent containing a hydroxyalkyl ether carboxylate and an oily component having a hydration rate of 100%. Moreover, Patent Document 4 discloses a skin cleanser composition containing a higher fatty acid salt, an amino acid-based polymer, and two or more types of water-soluble polymers having different ionicities.
On the other hand, hydroxystearic acid polymers have superior pigment dispersibility and are used in cosmetics. For example, Patent Document 5 discloses a liquid cosmetic characterized by containing (a) an extender powder, (b) 0.1% by weight to 30% by weight of an oily agent, and (c) 0.001% by weight to 3% by weight of polyhydroxystearic acid, and a hydroxystearic acid polymer is incorporated for the purpose of improving wettability of the powder and oily agent.
In addition, Patent Document 6 discloses an esterification reaction product obtained by esterifying dipentaerythritol and 12-hydroxystearic acid polymer, wherein the hydroxyl value of the aforementioned esterification reaction product is 20 mg KOH/g to 70 mg KOH/g, and the acid value is 3 mg KOH/g or less. Since the aforementioned esterification reaction product demonstrates high water holding properties and has favorable pigment dispersibility, use of the aforementioned esterification reaction product allows the obtaining of oil-in-water-type emulsion cosmetics and water-in-oil-type emulsion cosmetics that incorporate a large amount of water (and/or polyvalent alcohol) and demonstrate superior water retention stability and temporal stability.